In the recent past, a method for producing hydrogel-containing contact lenses has been developed which is more economical than either lathe cutting or spin casting, and provides better control over the final shape of the hydrated lens. This method involves direct molding of a monomer mixture wherein said mixture is dissolved in a non-aqueous, displaceable solvent. The mixture is placed in a mold having the precise shape of the final desired hydrogel (i.e., water-swollen) lens, and the monomer/solvent mixture is subjected to conditions whereby the monomer(s) polymerize, to thereby produce a polymer/solvent mixture in the shape of the final desired hydrogel lens.
After the polymerization is complete, the solvent is displaced with water to produce a hydrated lens whose final size and shape are quite similar to the size and shape of the original molded polymer/solvent article.
Such direct molding of hydrogel contact lenses is disclosed in Larsen, U.S. Pat. No. 4,495,313 and in Larsen et al., U.S. Pat. Nos. 4,680,336, 4,889,664 and 5,039,459. In addition, other patents to be considered include Larson U.S. Pat. No. 4,565,348; Okkada et al U.S. Pat. No. 4,347,198; Shepherd U.S. Pat. No. 4,208,364; Mueller et al EP-A-0493,320A2; and Wichterle et al U.S. Pat. No. RE 27,401 (U.S. Pat. No. 3,220,960). The disclosure of each of these patents is incorporated in its entirety herein by reference.
It would be advantageous to provide new and beneficial hydrogel-containing contact lenses, packaging systems for such lenses and methods of producing such contact lenses.